Relugolix and Nelfinavir: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 2, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Nelfinavir
Relugolix
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
Let me explain what's going on with these two medicines. Relugolix (Orgovyx) is a prostate cancer treatment, and nelfinavir (Viracept) is an HIV medicine. Nelfinavir can block a "pump" in your body called P-gp that normally helps clear relugolix. When that pump is slowed down, more relugolix can build up, which may raise the chance of side effects.
On top of that, both drugs can affect your heart's rhythm (something called the QT interval), and together that effect can add up. The good news is your care team can manage this by spacing the doses, watching you more closely, and keeping an eye on your heart and blood levels. Please don't change anything on your own, just talk with your doctor or pharmacist.
Effect: Increased relugolix exposure plus additive QT prolongation.
Mechanism: Nelfinavir inhibits P-gp-mediated efflux of relugolix (a P-gp substrate), increasing relugolix exposure; both agents can prolong the QT interval (additive PD effect). Neither is a prodrug here, so the direction is straightforward enhanced relugolix effect.
Evidence: Theoretical; severity rated major; onset unspecified.
Management:
- Avoid combination if possible.
- If unavoidable: give relugolix first, separate by at least 6 hours, monitor for adverse reactions more frequently.
- Relugolix may be interrupted up to 2 weeks for short P-gp inhibitor courses; if interrupted >7 days, restart with 360 mg loading dose then 120 mg daily.
- Correct electrolytes; consider periodic ECG and electrolyte monitoring, especially with QT risk factors.
What happens
Increased relugolix exposure and an increased risk of QT interval prolongation
Interaction Deep Dive
Concurrent administration of relugolix (a P-gp substrate) with P-gp inhibitors should be avoided, since this combination can raise relugolix exposure and thereby heighten the likelihood of adverse reactions. When coadministration cannot be avoided, give the relugolix-containing product first, allow a minimum of 6 hours between doses, and increase the frequency of monitoring for adverse reactions 12. Relugolix therapy may be paused for as long as 2 weeks to accommodate a brief course of a P-gp inhibitor, with relugolix resumed once the P-gp inhibitor has been stopped. Should the relugolix interruption exceed 7 days, reinitiate relugolix using a loading dose of 360 mg on day one, followed by 120 mg once daily thereafter 1. Using relugolix together with drugs that prolong the QT interval may produce additive QT interval effects. In patients with congenital long QT syndrome, congestive heart failure, or frequent electrolyte disturbances, as well as those receiving medications recognized to prolong the QT interval, weigh whether the benefits of androgen deprivation therapy such as relugolix justify the possible risks. Electrolyte abnormalities should be corrected, and periodic monitoring of ECGs and electrolytes should be considered 1.
Why it happens (mechanism)
Inhibition of P-gp-mediated efflux transport of relugolix; additive QT interval prolongation
How to manage this interaction
Your care team will weigh whether these two drugs should be used together at all, since avoiding the combination is preferred. If they decide you need both, here is what they typically do:
- Take your relugolix dose first, then separate it from nelfinavir by at least 6 hours.
- Watch you more closely for side effects.
- Possibly pause relugolix during a short course of nelfinavir, then restart it (with a loading dose if it was stopped for more than 7 days).
- Check your heart rhythm (ECG) and blood salts (electrolytes) periodically, and correct any electrolyte imbalances.
Keep taking both exactly as prescribed and ask your pharmacist or doctor before making any changes. Report symptoms like fainting, palpitations, or a fast or irregular heartbeat.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) Giving relugolix (a P-gp substrate) together with erythromycin (a P-gp and CYP3A inhibitor) raised the AUC of relugolix by 3.5-fold and the Cmax by 2.9-fold 1.
Common questions
Can I take Relugolix and Nelfinavir together?
Nelfinavir can raise relugolix levels and both can affect heart rhythm, so this combination is best avoided; if used together, your team will space the doses, monitor you closely, and check your ECG and electrolytes. Don't change anything on your own, talk with your doctor or pharmacist. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Relugolix and Nelfinavir interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Relugolix and Nelfinavir interaction managed?
Your care team will weigh whether these two drugs should be used together at all, since avoiding the combination is preferred. If they decide you need both, here is what they typically do: Take your relugolix dose first, then separate it from nelfinavir by at least 6 hours. Watch you more closely for side effects. Possibly pause relugolix during a short course of nelfinavir, then restart it (with… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Relugolix or Nelfinavir need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (2)
- Product Information: ORGOVYX oral tablets, relugolix oral tablets. Sumitomo Pharma America, Inc (per FDA), Marlborough, MA, 2025. DailyMed
- Product Information: MYFEMBREE(R) oral tablets, relugolix, estradiol, norethindrone acetate oral tablets. Myovant Sciences Inc (per FDA), Brisbane, CA, 2021. DailyMed
Keep reading about Nelfinavir
Keep reading about Relugolix
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